State environmental officials and federal agents were investigating the discovery of an unidentified white powder at a postal distribution center.

Department of Environmental Protection (searchofficials say an employee found the powder in an envelope Tuesday morning. The facility remains open, and officials say they've isolated the area where the powder was discovered.

The Wallingford (search) facility is the same postal center at which investigators found anthrax (searchspores in 2001. The substance found Tuesday has been taken for testing, DEP officials said.

The discovery of the powder comes a day after a suspicious white power that tested positive for ricin was found in Senate Majority Leader Bill Frist's office.

The powder was apparently delivered to the Republican senator's office through the mail system. More definitive tests were expected later Tuesday.